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为纪念本刊发行五十期,编辑部特约了井矿盐区的四川、湖南、云南、湖北省部分单位提供彩色照片,以作为本期彩色封面封底。
In order to commemorate the 50 issues of this issue, the editorial department has provided some photos of some units in Sichuan, Hunan, Yunnan and Hubei Provinces in Wells and Mines to serve as the back cover of the current color covers.